The present invention relates to the production of steel and, more particularly, the invention relates to a method and equipment for a multi-stage production of steel and formation of reaction slag, by means of blowing gaseous oxygen into and through the product, the oxygen may be blown directly or applied through oxygen carriers.
The method to which the invention pertains is basically quite different from conventional converter methods which can made variable through a variety of blowing techniques such as top blowing or through blowing from the bottom. Blowing a converter by means of oxygen or through blowing under utilization of inert gases such as argon and nitrogen has as its primary objective the improvement of the overall method of production with side effects of a beneficial nature arising to the equipment, but also for purposes of improving the final product steel. All known variations of the so-called LD process, such as any variation of flushing gas amount, improvement of after-burning of carbon monoxide and carbon dioxide, the guiding of slag, the resulting dephosphorization and desulphurization, the reduction of manganese burnoff and the like, have as a primary objective the improvement of the quality of steel under lower production costs, permitting also varying the scrap content in the converter. All this, however, requires that certain prescribed values and parameters be maintained, including here particularly the quantity of raw material variations of changes are limited and permitted to occur within in very tight limits only. This is particularly required with regard to the existing converter vessel, its capacities and operation of parameters.
Once a converter with blowing equipment has been installed and the installation has been completed, any variation, i.e., any flexible operation for matching the steel production in the converter to any particular requirements is limited to a great degree and requires, even in case of minor variations, considerable expenditures, and still often they can only be unsatisfactorily or incompletely fulfilled. Therefore, the LD process is very inflexible, in spite of the increasing tendency in modern industrial countries concerning the mass production of steel on one hand, and the increased demand for high quality steel on the other hand. These known converters are simply not well suited for that purpose, and they are particularly not well suited for varying the amounts of steel and the particular composition.
Independently from the foregoing, there has to be observed that the method outlined earlier and deviating from the LD method is known from the German patent No. 2,942,779. This particular patent discloses a method for working a particular amount of pig iron, but does not consider a broader scope of raw material which may include or is even exclusively determined by scrap iron.